I completely agree. Hans Spuhr showed me the 45 degree mount at the 2013 Shot Show. After seeing it, it seems completely ideal. Like you said, you can just rotate the gun to aquire the reflex sight, and you never even have to lift your head off the cheek rest.
I have a reflex sight mounted about the scope on my AR, and although it works ... I would do it differently now (and probably will at some point).
Here is a photo of the 45 degree Spuhr mount setup I was talking about seeing: